Documents, obtained by The Guardian, reportedly show several emails between the gunman Vester Flanagan, WDBJ-7's news director Dan Dennison, and several senior colleagues at the station.

In one memo, Mr Dennis warned Flanagan, known professionally as Bryce Williams, that in one month he had "behaved in a manner that has resulted in one or more of your co-workers feeling threatened or uncomfortable", according to the paper.

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After an initial warning to seek "employee assistance professionals" at a company called Health Advocate on 30 July 2012, he reportedly was given a final chance on Christmas Eve that year. Dennison reportedly emailed colleagues saying: "I'm not entirely sure where his head is at." He was fire three months later when police escorted him from the newsroom's building.

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Virginia shootings

13/13
Virginia shootings

Nearly two years later Mr Flanagan would take the lives of two of his former WDBJ-7 coworkers.

In 2014, he filed racial and sexual discrimination lawsuits against the station. The case was eventually dismissed.

“Your Honor, I am not the monster here. I get along with my current co-workers... That sure doesn’t sound like the monster I was painted to be,” he wrote in the filing. However, employees at the station vehemently deny these claims.

The Independent has reached out to WDBJ Television for comment.

It emerged after the death of Flanagan that a 23-page manifesto had been sent to ABC News, purportedly sent by a Bryce Williams.

In it, he blamed the murder on the Charleston Church massacre, in which nine black people were killed in South Carolina.

Referring to the Charleston gunman Dylann Roof, it read: "You want a race war (redacted)? BRING IT THEN YOU WHITE …(redacted)!!!"